!UPSTREAM: i965/gen7+: Implement fast color clear operation in blorp.

TODO:

- Test that the new blorp program puts the right data in the MCS
  buffer.

- When doing a fast color clear, flag the surface as needing a fast
  color resolve.

- Create a field in intel_mipmap_tree to store clear color bits.

- When configuring SURFACE_STATE, copy clear color bits from
  intel_mipmap_tree.

- In brw_blorp_clear_params constructor, if doing a fast clear, store
  appropriate bits in intel_mipmap_tree to represent the clear color.

- Support more than just (0.0, 0.0, 0.0, 0.0) in
  is_color_fast_clear_compatible().